Tank valves of the class contemplated by this invention are intended to supply water to a storage tank so as to tend to maintain the water level at some predetermined storage level. Especially in tank valves for commodes, they are accompanied by a flush valve.
The flush valve is closed at the end of each discharge (flushing) cycle. At the end of the flushing cycle, the water in the tank must be replenished to be available for the next cycle. The tank valve is provided for this purpose. It is sensitive to the water level that exists in the tank. When the water level is below the intended storage level, the tank valve opens to flow, and will remain open to flow until the water again rises to the intended storage level.
These statements describe very conventional means to store and discharge water for flushes. The art is extensively developed. The tank valve is invariably provided with a float of some kind which, when its elevation coincides with the intended storage level, closes off the tank valve.
Tank valves which include a float on a pivoted arm to control the tank valve by pressing as a lever on a valve mechanism are exemplified by Antunez U.S. Pat. No. 3,070,118. This is perhaps the most widely used type of tank valve at the present time.
There is another type of tank valve which relies on a differential pressure instead of a direct force linkage to open and to close a tank valve. In this type of tank valve, its opening and closing are determined by a diaphragm or piston whose position is the consequence of a differential pressure and area. The pressures involved are atmosphere and the water supply line pressure. The selective differential is developed by closing or opening a vent port in response to the level of a float.
The opening of such a valve involves no special problems despite the fact that the float and the valve workings are not directly linked, because the weight of the unsupported float against the valve working will be sufficient to assure an opening action.
The closure of the valve involves a very different situation. Here the float gradually rises with the water level, and ultimately freely and independently moves away from the valve workings. The theory is that the parts of the workings which actually control the valve setting will follow the float upwardly as far as necessary as a consequence of internal fluid forces in the valve even though the physical parts are not directly linked together. This gives rise to an occasional problem when the parts become stuck. This can arise from occasional dimensional interferences, from silting up, and from liming up, as examples. Because the float does not then tend to free the linkage, the valve can remain open when it should instead be shut.
It is an object of this invention to provide a float-controlled differential-pressure type tank valve whose valve workings and its float are not directly linked to one another, and in which means is provided for the valve to boost the valve workings when the tank valve is to be closed so as to assure closing of the valve.